Molecular Dynamics of Artificially Pair-Decoupled Systems: An Accurate Tool for Investigating the Importance of Intramolecular Couplings

We propose a numerical technique to accurately simulate the vibrations of organic molecules in the gas phase, when pairs of atoms (or, in general, groups of degrees of freedom) are artificially decoupled, so that their motion is instantaneously decorrelated. The numerical technique we have developed is a symplectic integration algorithm that never requires computation of the force but requires estimates of the Hessian matrix. The theory we present to support our technique postulates a pair-decoupling Hamiltonian function, which parametrically depends on a decoupling coefficient α ∈ [0, 1]. The closer α is to 0, the more decoupled the selected atoms. We test the correctness of our numerical method on small molecular systems, and we apply it to study the vibrational spectroscopic features of salicylic acid at the Density Functional Theory ab initio level on a fitted potential. Our pair-decoupled simulations of salicylic acid show that decoupling hydrogen-bonded atoms do not significantly influence the frequencies of stretching modes, but enhance enormously the out-of-plane wagging and twisting motions of the hydroxyl and carboxyl groups to the point that the carboxyl and hydroxyl groups may overcome high potential energy barriers and change the salicylic acid conformation after a short simulation time. In addition, we found that the acidity of salicylic acid is more influenced by the dynamical couplings of the proton of the carboxylic group with the carbon ring than with the hydroxyl group.

Unsupervised Machine Learning Neural Gas Algorithm for Accurate Evaluations of the Hessian Matrix in Molecular Dynamics

The Hessian matrix of the potential energy of molecular systems is employed not only in geometry optimizations or high-order molecular dynamics integrators but also in many other molecular procedures, such as instantaneous normal mode analysis, force field construction, instanton calculations, and semiclassical initial value representation molecular dynamics, to name a few. Here, we present an algorithm for the calculation of the approximated Hessian in molecular dynamics. The algorithm belongs to the family of unsupervised machine learning methods, and it is based on the neural gas idea, where neurons are molecular configurations whose Hessians are adopted for groups of molecular dynamics configurations with similar geometries. The method is tested on several molecular systems of different dimensionalities both in terms of accuracy and computational time versus calculating the Hessian matrix at each time-step, that is, without any approximation, and other Hessian approximation schemes. Finally, the method is applied to the on-the-fly, full-dimensional simulation of a small synthetic peptide (the 46 atom N-acetyl-l-phenylalaninyl-l-methionine amide) at the level of DFT-B3LYP-D/6-31G* theory, from which the semiclassical vibrational power spectrum is calculated.

Between history and gossip: the state of women relative to syphilis, a traditionally male disease

Despite the new World Health Organization data remind us how syphilis is a disease which affects both sexes equally, this pathology has always been mainly considered a male disease. While several famous men are known to be affected by syphilis, there are very few women affected by this pathology of which we have historical records. Through the lives of Mary Todd Lincoln, Catherine of Aragon, Karen Blixen and Florence Foster Jenkins, this article would like to grant dignity to all the women who contracted syphilis in the wrong historical era where, for a woman, admitting to contracting it was shameful. Through the important women who lived their lives fighting against this disease and its complications, we would like to pay tribute to all those women who still today, in an era of antibiotics and where syphilis is a treatable pathology, they cannot be cured because they are both geographically and socially disadvantaged.

A short novel about the spread of two important diseases in history: syphilis and SARS

Throughout the centuries, the undefended nature of man has very often manifested in cases of epidemics, which have determined scenarios of suffering and death. Through “historical” observation lens, it is possible to understand the relationship between the spread of viruses, bacteria and parasites responsible for these epidemics and the displacement of ancient or contemporary travellers. We have analysed two infective diseases, syphilis and SARS, and their role in history and in medicine.

Rehabilitation procedures in the management of gait disorders in the elderly

Gait disorders are common and very disabling in elderly people, leading to an increase of risk of falling and reductions in quality of life. So far, many clinical classifications of gait disorders in the elderly population have been proposed. Here we suggest a novel categorization of gait disorders in elderly people, which takes into account the several resources required during gait. The biomechanical constraints, movement and sensory strategies, orientation in space, control of dynamics and cognitive processing are essential to perform safely gait. Moreover, the strictly connection between gait and balance has been discussed. According to this perspective, a literature search was performed including studies investigating the rehabilitation procedures in the management of balance and gait disorders in elderly people. Training aimed at improving muscle strength and flexibility, movement strategies, sensorimotor integration and sensory reweighting processes, balance in static and dynamic conditions and cognitive strategies have been proposed as possible therapeutic approaches in elderly people affected by gait disorders. Moreover, the role of new technological devices in improving balance and gait control has been also described. A multidisciplinary and interdisciplinary approach is fundamental for the management of gait disorders in elderly people. Rehabilitation procedures should take into consideration all the potential constraints involved in gait disorders in order to select the most appropriate intervention.

Dexamethasone's effect in the retrocochlear auditory centers of a noise-induced hearing loss mouse model

OBJECTIVE

Examine prophylactic effects of dexamethasone (Dex) in retrocochlear auditory centers in a noise-induced hearing loss (NIHL) mouse model.

STUDY DESIGN

Prospective animal study.

SETTING

Academic research center.

SUBJECTS AND METHODS

Thirty-two mice were divided into control, untreated, saline (2 and 10 µL), and Dex (2 and 10 µL) groups. Dex was applied intratympanically (IT) prior to 110 to 120 dB noise over 6 hours. Auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) were performed at 1 day, 1 week, 1 month, and 2 months. Retrocochlear neuronal cells were labeled with FluoroGold and counted. Hair cells of the organ of Corti were labeled with fluorescein isothiocyanate-conjugated phalloidin and counted.

RESULTS

Auditory brainstem response thresholds of untreated NIHL, 2 and 10 µL IT saline, and 2 and 10 µL IT Dex were 21.7 ± 2.9 dB, 20 ± 0 dB, 20 ± 5 dB, 18.3 ± 2.9 dB, and 18.3 ± 2.9 dB, respectively. At 1-day post NIHL, all groups demonstrated profound hearing loss. At 2 weeks, 2 and 10 µL Dex thresholds improved to 47.5 ± 3.5 dB and 48.8 ± 18.9 dB, respectively, whereas the untreated and saline groups remained unchanged. Mean cell counts in the cochlear nucleus (CN), superior olivary complex (SOC), and lateral lemniscus (LL) of control mice were 1483 ± 190, 2807 ± 67, and 112 ± 20, respectively. After acoustic trauma, the untreated, saline, and 2 µL Dex groups yielded decreased neuronal counts in the SOC. In contrast, the 10 µL Dex group had 1883 ± 186 (CN), 2774 ± 182 (SOC), and 166 ± 18 (LL). There was sporadic hair cell loss for all traumatized groups.

CONCLUSION

Our NIHL mouse model demonstrated dose-dependent Dex pretreatment otoprotection against NIHL with preservation of retrocochlear auditory neurons.

Rehabilitation of brachial plexus injuries in adults and children

Management of brachial plexus injury sequelae is a challenging issue in neurorehabilitation. In the last decades great strides have been made in the areas of early diagnosis and surgical techniques. Conversely, rehabilitation of brachial plexus injury is a relatively unexplored field. Some critical aspects regarding brachial plexus injury rehabilitation have to be acknowledged. First, brachial plexus injury may result in severe and chronic impairments in both adults and children, thus requiring an early and long-lasting treatment. Second, nerve damage causes a multifaceted clinical picture consisting of sensorimotor disturbances (pain, muscle atrophy, muscle weakness, secondary deformities) as well as reorganization of the Central Nervous System that may be associated with upper limb underuse, even in case of peripheral injured nerves repair. Finally, psychological problems and a lack of cooperation by the patient may limit rehabilitation effects and increase disability. In the present paper the literature concerning brachial plexus injury deficits and rehabilitation in both adults and children was reviewed and discussed. Although further research in this field is recommended, current evidence supports the potential role of rehabilitation in reducing both early and long-lasting disability. Furthermore, the complexity of the functional impairment necessitates an interdisciplinary approach incorporating various health professionals in order to optimizing outcomes.

Stimulating visual exploration of the neglected space in the early stage of stroke by hemifield eye-patching: a randomized controlled trial in patients with right brain damage

BACKGROUND

It has been well established that the presence of neglect is a predictor of poor functional outcome after stroke. Most rehabilitation studies on neglect have been performed with at least two months post-stroke. However, a recent series of stroke management indications highlight the importance of early rehabilitation treatment and evidence regarding neglect rehabilitation in the early phase after stroke is needed.

AIM

To evaluate the effectiveness of right half-field patches in treating neglect in patients during the early phase of stroke.

DESIGN

Randomized controlled trial.

SETTING

Acute care setting in an urban general hospital.

POPULATION

Eighteen patients with left unilateral neglect recruited among 56 patients consecutively admitted with right hemispheric stroke.

METHODS

The patients were evaluated at pre-treatment, post-treatment, and at a 7-day follow-up. The experimental group received right half-field patch treatment (n=10) for approximately 8 hours a day for 15 consecutive days. The control group received visual scanning training (n=8) for 40 minutes every weekday in a 15 day period.

RESULTS

Both groups significantly improved their performance in all outcome measures. No difference in the amount of improvement between the two groups was found.

CONCLUSION

Right half-field eye patching could be a promising technique for treating visual spatial neglect during the early stages of stroke.

CLINICAL REHABILITATION IMPACT

The eye-patching technique may represent an easily applicable and inexpensive method for neglect rehabilitation in the early stage after stroke.

Applicability of a new robotic walking aid in a patient with cerebral palsy. Case report

BACKGROUND

Gait training with the help of assistive technological devices is an innovative field of research in neurological rehabilitation. Most of the available gait training devices do not allow free movement in the environment, which would be the most suitable natural and motivating condition for training children with neurological gait impairment.

AIM

To evaluate the potential applicability of a new robotic walking aid as a tool for gait training in non-ambulatory children with Cerebral Palsy.

DESIGN

Single case study

SETTING

Outpatient regimen

POPULATION

A 11-years-old child unable to stand and walk independently as a result of spastic tetraplegic cerebral palsy (CP).

METHODS

The experimental device was a newly actuated version of a dynamic combined walking and standing aid (NF-Walker®) available in the market which was modified by means of two pneumatic artificial muscles driven by a foot-switch inserted in the shoes. The child was tested at baseline (while maintaining the standing position aided by the non-actuated NF-Walker®) and in the experimental condition (while using the actuated robotic aid). The outcome measures were: 2-minute walking test, 10-metre walking test, respiratory and heart parameters, energy cost of locomotion.

RESULTS

At baseline, the child was unable to perform any autonomous form of locomotion. When assisted by the actuated aid (i.e. during the experimental condition), the child was successful in moving around in his environment. His performance was 19.63 m in the 2-minute walking test and 64 s in the 10-metre walking test. Respiratory and heart parameters were higher than healthy age-matched children both at baseline and in the experimental condition. The energy cost of gait, which was not valuable in the baseline condition, was significantly higher than normality during the experimental condition.

CONCLUSION

The new robotic walking aid may help children suffering from CP with severe impairment of gait to move around in their environment.

CLINICAL REHABILITATION IMPACT

This new robotic walking device may have a potential impact in stimulating the development and in training of gait in children with neurological gait impairment. Future studies are warranted in order to test this hypothesis.

Rehabilitation procedures in the management of spasticity

Spasticity is a major disabling symptom in many patients with spinal and/or cerebral lesions. During functional movements, spasticity manifests itself within the complex condition of the "spastic movement disorder". The pathophysiology of the spastic movement disorder relies on multiple factors including abnormal supraspinal drive, abnormal control of reflex activities, and changes in muscle mechanical properties. The most widely used procedures for management of spasticity are represented by pharmacological treatment aimed at inhibiting reflex hyperexcitability. In the last decades, several non pharmacological procedures for treating spasticity have been put forward, including muscle stretching, muscle reinforcement, physical agents and pain management. These procedures may have both neurophysiological and biomechanical effects on the spastic movement disorder. In the present paper, the literature concerning non-pharmacological procedures in the treatment of spasticity was reviewed and discussed, taking into account the multifaceted pathophysiology of the spastic movement disorder. Although further research in this field is recommended, existing evidence supports the potential role of rehabilitation interventions as a therapeutic tool, which could be integrated with traditional pharmacological procedures in the management of the spastic movement disorder.

Augmentative and alternative communication in adolescents with severe intellectual disability: a clinical experience

AIM

Augmentative and alternative communication devices proved to be effective in patients with severe intellectual disability to overcome their communication impairments. In order to give a contribution for design of augmentative and alternative communication systems that better meet the needs of beginning communicators we decided to report our clinical experience about using augmentative and alternative communication in adolescents with severe intellectual disability.

METHODS

Five patients who underwent a long time traditional speech rehabilitation program (at least 5 years) with scant improvements in linguistic function were recruited and evaluated by means of the Vineland Adaptive Behaviour Scale before and after a three years augmentative and alternative communication intervention carried out by a multidisciplinary team.

RESULTS

After the rehabilitative intervention patients showed an improvement in communication, daily living skills and socialization as measured by the Vineland Adaptive Behaviour Scale.

CONCLUSION

Augmentative and alternative communication is an effective rehabilitation approach to people with severe intellectual disability and impairments in linguistic expression. Moreover augmentative and alternative communication is a useful tool allowing these patients to increase their social participation also enhancing their self-esteem. Our clinical experience confirmed these topics also in adolescents who underwent a long time traditional speech rehabilitation program with scant improvements, providing practical information to clinicians.

Effect of strontium and gelatin on the reactivity of alpha-tricalcium phosphate

The hydrolysis reaction of alpha-tricalcium phosphate (alpha-TCP) is of great interest because of its widespread use in the preparation of biomaterials for hard tissue repair. The aim of this study was to investigate how this reaction is influenced by the presence of a bioactive ion, Sr(2+), and of a biopolymer, gelatin, which were previously reported to affect the setting reaction of alpha-TCP-based cements. Hydrolysis experiments were carried out at different Sr(2+) concentrations (0, 5, 10, 20 at.%) in solutions at different gelatin concentrations (0, 0.1, 0.5, 1.0 wt.%). The results indicate that Sr(2+) delays the conversion of alpha-TCP into calcium-deficient hydroxyapatite (CDHA). The structural and morphological modifications of CDHA obtained from solutions at increasing Sr(2+) concentrations indicate that during hydrolysis strontium enters the structure of CDHA, where it partially substitutes for calcium. On the contrary, alpha-TCP hydrolysis rate increases on increasing gelatin concentration. Gelatin promotes conversion of alpha-TCP into octacalcium phosphate, and strongly interacts with the nucleating and growing crystals.

A modified constraint-induced movement therapy (CIT) program improves paretic arm use and function in children with cerebral palsy

AIM

Constraint-induced movement therapy (CIT) is a rehabilitation intervention put forward by Taub and colleagues for sensorimotor disorders in children with hemiparesis, comprising consisting of the restraint of the unaffected arm and concurrent intensive training of the affected arm for six hours/day for two weeks. The aim of this study was to evaluate the effectiveness of a modified CIT program (mCIT) characterized by restraining the unaffected hand with a cotton mitten during daily activities and a reduced intensity training program for two h/week for five weeks.

METHODS

Ten children (age: 1-9 years) with hemiparetic cerebral palsy were enrolled in a randomized, cross-over study in which the effects of a mCIT and a conventional physiotherapy program were compared. The amount of use and the functional performance of the affected arm were evaluated by means of two specifically devised tests (Use and Function Test). A further test evaluated functional performance during bimanual tasks. These measures showed a good inter-rater and inter-session reliability. All tests were administered before, at the end and four weeks after treatment.

RESULTS

Significant differences between the two therapeutic approaches were evidenced in both affected arm use (P=0.008) and function (P=0.018). These improvements maintained at the follow-up (Use Test P=0.07; paretic arm function P=0.012). Bimanual function performance showed a trend towards improvement in both post-treatment and follow-up testing. The conventional physiotherapy group did not show any improvement in any outcome measure.

CONCLUSIONS

The mCIT program proposed in the present study showed to be a promising rehabilitative procedure in children with congenital arm paresis after cerebral palsy.

Activation of the Gal1 Gene of Yeast by Pairs of 'Non-Classical' Activators

Eukaryotic transcriptional activators work by recruiting to DNA the transcriptional machinery, including protein complexes required for chromatin modification, transcription initiation, and elongation. Which of these complexes must be directly recruited to trigger transcription? We test various "non-classical" transcription activators (comprising a component of the transcriptional machinery fused to a DNA binding domain) for their abilities to activate transcription of a chromosomally integrated reporter in yeast. Among these newly constructed fusion proteins, none efficiently activated transcription when working on its own. However, in several instances transcription was activated by a pair of such fusion proteins tethered to adjacent sites on DNA. In each of these cases, one fusion protein bore a component of the SAGA complex, and the other bore a component of the Mediator complex. Transcription was also activated by certain tripartite fusion proteins comprising a Mediator and a SAGA component fused to a DNA binding domain. The results are consistent with the finding that the classical activator Gal4, working at the GAL1 promoter, activates transcription by (at least in part) independently recruiting SAGA and Mediator.

Nanocrystals of magnesium and fluoride substituted hydroxyapatite

Hydroxyapatite nanocrystals synthetized in the presence of different concentrations of magnesium and fluoride ions in solutions--1, 5 and 10 at.% have been submitted to a structural and chemical characterization. The syntheses were carried out in the presence of low molecular weight polyacrylic acid, which has been verified to inhibit hydroxyapatite crystallization. The polyelectrolyte is adsorbed into the crystals during the synthesis and provokes a reduction of the mean crystal sizes. The reduction is greater along the direction orthogonal to the c-axis, suggesting a preferential adsorption of the polyelectrolyte on the crystalline faces parallel to the c-axis. Both magnesium and fluoride can be incorporated into the hydroxyapatite structure. On the basis of the values of the lattice constants and of the magnesium relative content of the solid phase, it can be suggested that probably just a part of magnesium is substituted for calcium, the remainder being adsorbed on the crystal surface. However, magnesium destabilizes the apatitic structure favouring its thermal conversion into beta-tricalcium phosphate, and displays an inhibiting effect on the crystallization of hydroxyapatite. This last effect is enhanced by the simultaneous presence of polyacrylic acid. Fluoride substitution for hydroxyl ions into hydroxyapatite structure induces a slight increase of the crystal sizes along the c-axis direction. The data indicate that the experimental approach can be successfully used to prepare nanoapatite with crystallinity, crystal dimensions, composition, structure and stability very close to those characteristics of biological apatites.

In vitro calcified tendon collagen: an atomic force and scanning electron microscopy investigation

Atomic force microscopy (AFM), scanning electron microscopy and X-ray energy dispersive spectroscopy have been performed on decalcified turkey tendons submitted to in vitro calcification in order to investigate the morphology and the surface relationships between the inorganic phase and the collagen fibres during deposition and compare with those found for physiologically calcified samples. 'Tapping mode' AFM was used to reduce the vertical force applied to the samples, which were examined without any preparation. A further characterization has been carried out by means of X-ray diffraction, infrared absorption and chemical analyses. The observations indicate that the inorganic phase deposited on collagen fibres during in vitro calcification is poorly crystalline B carbonated apatite. The composition, structure and dimensions of apatitic crystallites, as well as their orientation with respect to collagen fibrils, are very similar to those characteristic of physiologically calcified tissues. However, the crystallites seem to be nucleated on the fibril surface, without appreciably affecting the molecular packing of collagen.

X-ray diffraction study of in vitro calcification of tendon collagen

Decalcified samples of turkey leg tendon were submitted to in vitro calcification in the presence of metastable solutions of calcium phosphate at different concentrations. The structural relationship between apatitic deposits and collagen fibrils was examined by high- and small-angle X-ray diffraction using conventional and synchrotron radiation sources. At high supersaturation the apatitic crystallites were deposited on the collagen fibrils with their crystallographic c-axis preferentially oriented parallel to the fibril axis. At lower supersaturation, a fraction of the apatitic crystallites also grew with the c-axis preferentially oriented parallel to the collagen fibril axis, whereas other exhibited a preferential orientation perpendicular to the fibril axis. The analysis of the small-angle X-ray diffraction data indicates that the deposition of the apatitic phase in the sample stored in solution at lower supersaturation induced modifications of the collagen electron density distribution in the axial direction, which can be attributed to the deposition of the inorganic crystallites inside the gap region of the collagen structure.

[Neoplasms of the parotid space. Therapeutic guides]

The Authors report about 161 neoplasms of the parotid space observed in the ten-year period since 1977 to 1987. With the exception of carcinomas and mucoepidermoid tumors, always to be treated by total parotidectomy, for the remaining pathology of the gland either neoplastic or not neoplastic as well as the extra salivary tissues diseases, the Authors suggest a conservative surgical treatment, in respect of the facial nerves and of the salivary tissue not directly involved.

Dynamic flexible intramedullary nailing in the treatment of fractures of the femoral diaphysis

The authors report their experience in the treatment of fractures of the femoral shaft by flexible intramedullary nailing. This method involves particular biomechanical characteristics that permit stable fixation of the fracture while allowing early and complete functional recovery in the affected limb. The results are reported in 114 cases.

Thin-layer chromatographic determination of indolic tryptophan metabolites in human urine using Sep-Pak C18 extraction

Tryptophan and some of its indole metabolites were separated by thin-layer chromatography, stained with the Van Urk--Salkowski reagent, and quantitated by scanning densitometry. The application of this technique for the detection of the indoles in urine samples, employing Sep-Pak C18 cartridges for extraction, was demonstrated. The proposed method is simple and accurate. The detection limits were 2 micrograms/ml 5-hydroxytryptophan, 1.75 micrograms/ml 5-hydroxyindolyl-3-acetic acid, 1.5 micrograms/ml tryptophan, 0.8 micrograms/ml indolyl-3-acetic acid, 0.9 micrograms/ml indolyl-3-butyric acid, 1.75 micrograms/ml serotonin, and 1.25 micrograms/ml tryptamine.